68 AFRICAN LONG-TAILED NIGHT-JAR. 



birds, defy all clear description, and renders it im- 

 possible, by these indications only, to discriminate 

 the species- We consider it, therefore, altogether 

 hopeless to determine the identity of the greater 

 portion of those which have been described but not 

 figured; and even many of these latter will long 

 remain undetermined, from the inaccuracy which 

 belongs to the figures themselves and to the loose- 

 ness of their descriptions. 



On examining an extensive series of these birds 

 in our museum, with a view to determine both the 

 species, and the natural groups among those that 

 have been left by authors in the old genus Capri- 

 mulgus, we have ascertained that two very distinct 

 types of form (which we suspect are the typical and 

 the sub-typical) are confounded under this latter 

 denomination. In one of these, to which we retain 

 the old name of Caprimulgus, the two lateral toes of 

 the foot are of the same length, while in the other, 

 which we propose to designate as the genus Scotor- 

 m's, the inner toe is longer than the outer. That 

 this remarkable variation of structure should not 

 have been hitherto noticed, is surprising; since it 

 facilitates, more than any other character yet dis- 

 covered, the arrangement of the species, and con- 

 sequently their determination. It has, however, 

 this temporary evil, that it will oblige us to re-ex- 

 amine all those that have been already described, 

 for the purpose of ascertaining the structure of their 

 feet, a circumstance which all writers appear to have 

 overlooked. In both these groups the tail is either 



